What is created when complement proteins form a membrane attack complex on pathogens?

The formation of a membrane attack complex by complement proteins leads to the creation of pores in the pathogen's membrane. This process is a key aspect of the immune response, as the membrane attack complex (MAC) inserts itself into the lipid bilayer of the foreign pathogen's cell membrane, creating large openings or pores. These pores disrupt the integrity of the membrane, leading to cell lysis and death of the pathogen. This is a vital mechanism in innate immunity, as it directly enhances the host's defense against infections by effectively neutralizing a wide range of pathogens, including bacteria and some viruses.